Respiratory protective devices have been in use in workplace and emergency type settings for many years. While these devices are very effective for those professionals that wear them, their bulky design and high expense can be a deterrent to the private individual. Furthermore, workers may forego the use of mask type respirators for periods of short term exposure where the time involved in retrieving, fitting, and replacing the respirator is thought to outweigh the potential harm to the employee. Unfortunately, the uninformed worker can experience lasting detrimental effects to his health from even short-term exposure to certain airborne contaminants.
Furthermore, the threat of airborne contaminants to those who do not regularly encounter such particles, including chemical, inorganic, and biological contaminants, is becoming more common. With city overcrowding and ever decreasing living spaces, contact with other people is a fact of daily life. Many individuals are likely to have close contact with sick persons on a daily basis. In the event of an emergency, an individual may not have time to retrieve a large mask type respirator from storage that could effectively filter inhaled air. Further, a person may find himself in a situation where access to a mask type respirator is impossible. By the time such person is able to retreat from the infected area, he may have already inhaled harmful contaminants.
While several personal respirators have been described in the prior art, each has various drawbacks and flaws that make them unsuitable for portable, individual use. Typically these personal respiratory filters provide inadequate airflow, thus requiring strenuous physical exertion by the user due to either or both of the airflow resistance through the filter media, and large dead space volume. Upon exhalation, not all air is forced from the filter. The filter volume occupied by this exhaled air, which is relatively high in carbon dioxide and other waste gasses, is the dead space. The dead space gasses are reinhaled prior to inhaling the relatively oxygen rich “new” air. If the dead space is too large, or the flow resistance is too great, extra exertion by the user can easily cause hyperventilation and unconsciousness, thus prolonging exposure to the airborne contaminants.
Despite the amount of prior art, there remains a need for an easily portable, inexpensive and wholly disposable personal breathing filter that can effectively remove both organic and inorganic particles from inhaled air, while not requiring increased effort by the user to maintain normal breathing.